Notices
Pre-Power Stroke Diesel (7.3L IDI & 6.9L) Diesel Topics Only

Brake booster issues 88 f250 7.3L

 
  #1  
Old 06-11-2019, 12:06 PM
Tbrad003
Tbrad003 is offline
New User
Thread Starter
Join Date: Feb 2019
Posts: 20
Tbrad003 is starting off with a positive reputation.
Brake booster issues 88 f250 7.3L

I suddenly had lost brakes like the pump or the booster went out, but when I took of the house leading into the booster it had suction so I can tell if itís my vacum pump, my booster and I already bleed brakes and changed calipers.
 
  #2  
Old 06-11-2019, 02:32 PM
Olds64's Avatar
Olds64
Olds64 is offline
Posting Guru
Join Date: Jun 2017
Location: Edmond, OK
Posts: 1,140
Olds64 is starting off with a positive reputation.
To verify that the vacuum booster is working depress the brake pedal with the engine OFF. Start the engine and when the vacuum booster gets vacuum from the vacuum pump it will cause the brake pedal to pull down to the floor.

Does your 7.3l have an automatic or manual?
 
  #3  
Old 06-11-2019, 03:20 PM
Tbrad003
Tbrad003 is offline
New User
Thread Starter
Join Date: Feb 2019
Posts: 20
Tbrad003 is starting off with a positive reputation.
It has the four speed with an overdrive so five-speed
 
  #4  
Old 06-12-2019, 07:15 AM
Olds64's Avatar
Olds64
Olds64 is offline
Posting Guru
Join Date: Jun 2017
Location: Edmond, OK
Posts: 1,140
Olds64 is starting off with a positive reputation.
Ok. A faulty vacuum pump will cause the C6 to shift poorly.

You can put a vacuum gauge on one of the lines and see how much vacuum your pump is pulling if you're still wondering about the condition of the vacuum pump.
 
  #5  
Old 06-12-2019, 03:39 PM
DarkOverCast
DarkOverCast is offline
Elder User
Join Date: May 2015
Posts: 807
DarkOverCast is gaining momentum as a positive member of FTE.
Originally Posted by Olds64 View Post
Ok. A faulty vacuum pump will cause the C6 to shift poorly.

You can put a vacuum gauge on one of the lines and see how much vacuum your pump is pulling if you're still wondering about the condition of the vacuum pump.
This is what I would recommend. Mine got weak and was only pulling 15hg and it wasn't enough to keep up with my booster.
 
  #6  
Old 06-13-2019, 09:58 PM
lonewolf_'s Avatar
lonewolf_
lonewolf_ is offline
Senior User
Join Date: May 2019
Posts: 159
lonewolf_ is starting off with a positive reputation.
Originally Posted by Olds64 View Post
Ok. A faulty vacuum pump will cause the C6 to shift poorly.

You can put a vacuum gauge on one of the lines and see how much vacuum your pump is pulling if you're still wondering about the condition of the vacuum pump.

while the gauge is a great idea ..... beware that you could also have a Vacuum leak and the pump could be just fine but not able to keep up with the leak, you need to Isolate the pump from the Vacuum systems to really test it, the POD should hold Vacuum after it stops running too.
 
  #7  
Old 06-14-2019, 08:20 AM
Olds64's Avatar
Olds64
Olds64 is offline
Posting Guru
Join Date: Jun 2017
Location: Edmond, OK
Posts: 1,140
Olds64 is starting off with a positive reputation.
Originally Posted by lonewolf_ View Post
the POD should hold Vacuum after it stops running too.
I didn't know our trucks had a vacuum reservoir.

Here's how to id a vacuum leak.


 
  #8  
Old 06-14-2019, 02:57 PM
lonewolf_'s Avatar
lonewolf_
lonewolf_ is offline
Senior User
Join Date: May 2019
Posts: 159
lonewolf_ is starting off with a positive reputation.
the POD is the Pump Diaphragm with check Valve assemblies not an Accumulator AKA Vacuum Tank.... but since you mention a "vacuum reservoir" it really wouldn't be a bad Idea to add one..... the best way to detect a Vacuum leak is with Helium, but I digress




Of course the Vacuum systems on our trucks are nothing more than a leak in the first place .... so is a moot point to think you could have no leak as it is harder to hold Vacuum than it is to hold Pressure.... and I doubt most DIY'ers will have a Vacuum leak detector and BTW a little shot of R134A and your AC leak detector could be used too
 
  #9  
Old 06-14-2019, 03:25 PM
lonewolf_'s Avatar
lonewolf_
lonewolf_ is offline
Senior User
Join Date: May 2019
Posts: 159
lonewolf_ is starting off with a positive reputation.
this is a Vacuum Leak....... IF you sprayed a little R134A on it and had your detector near the POD outlet ..... so don't be blowing Smoke


 
  #10  
Old 06-14-2019, 04:41 PM
Tbrad003
Tbrad003 is offline
New User
Thread Starter
Join Date: Feb 2019
Posts: 20
Tbrad003 is starting off with a positive reputation.
I donít think the lines are leaking I replaced the booster yesterday and was going to check the vacum pump today
 
  #11  
Old 06-14-2019, 04:42 PM
Tbrad003
Tbrad003 is offline
New User
Thread Starter
Join Date: Feb 2019
Posts: 20
Tbrad003 is starting off with a positive reputation.
And also mine does not have the c6 in it so thatís wouldnít be the issue
 
  #12  
Old 06-14-2019, 05:34 PM
lonewolf_'s Avatar
lonewolf_
lonewolf_ is offline
Senior User
Join Date: May 2019
Posts: 159
lonewolf_ is starting off with a positive reputation.
Originally Posted by Tbrad003 View Post
And also mine does not have the c6 in it so thatís wouldnít be the issue
Exactly .....

and the Vacuum Leaking Booster check valve I Posted wouldn't pose a real issue either, the booster would still work fine....recovery time might be a bit delayed is all.

my question to you is....... do you have a Hard Pedal or is the issue that the pedal goes to the floor board ? a failed booster generally leads to a Hard pedal

the only thing I can say is IF the booster has failed your brakes work like manual Brakes with no power assist
 
  #13  
Old 06-14-2019, 06:38 PM
Tbrad003
Tbrad003 is offline
New User
Thread Starter
Join Date: Feb 2019
Posts: 20
Tbrad003 is starting off with a positive reputation.
Yes I have a stiff shower peda itís like the booster is bad but I just replaced it so it can be the booster or the master SIL annoyed
 
  #14  
Old 06-14-2019, 07:25 PM
lonewolf_'s Avatar
lonewolf_
lonewolf_ is offline
Senior User
Join Date: May 2019
Posts: 159
lonewolf_ is starting off with a positive reputation.
the rod adjustment should be about 25 mm ..... and the advice of using a vacuum Gauge to see what your line vacuum is will help you



I think it's time to add my Signature..........


My Standard Disclaimer as follows......................................

This information is provided free of charge and is probably worth precisely what you paid for it. If you build one of these devices, it is likely that it will fly apart and kill everyone within 5 blocks. Construct and use at your own risk.

 
  #15  
Old 06-15-2019, 12:02 AM
90Ford73
90Ford73 is offline
Senior User
Join Date: Oct 2014
Location: Alberta Eh
Posts: 129
90Ford73 is starting off with a positive reputation.
If the vacuum pump is shot you will have a hard pedal. When you shut off the truck and pump the pedal, itís normal for a few pumps and then starts getting harder as you consume the remaining vacuum because the pump isnít working.

If the booster is shot you will have a soft pedal like stepping on a plum. It will go down to the floor almost all the way before the truck decides it wants to stop. It is most noticeable going down a steep hill on the highway with your left turn at the bottom...

My master cylinder leaked into my booster causing the soft pedal no brake situation. To set the rod that goes into the master cylinder the instructions said to set it flush with the booster face. I didnít do that cause it was easier to buy both assembled and install as one unit.
 

Thread Tools
Search this Thread

Contact Us - About Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.